Turbo charged engines utilize a Charge Air Cooler (CAC) to cool compressed air from the turbocharger, before it enters the engine. Ambient air from outside the vehicle travels across the CAC to cool intake air passing through the inside of the CAC. Condensate may form in the CAC when the ambient air temperature decreases, or during humid or rainy weather conditions, where the intake air is cooled below the water dew point. Condensate may collect at the bottom of the CAC, and then be drawn into the engine at once during acceleration (or tip-in) increasing the chance of engine misfire.
A multi active grille shutter system, for example a dual grill system, located at a front end of a vehicle may control ambient airflow to the engine components. An upper group of grille shutters may control airflow to a radiator while a lower group of grille shutters may control airflow to the charge air cooler. In one example, the upper and lower groups of grille shutters may be actuated together with a single motor. However, actuating the upper and lower groups of grille shutters together may not allow for both increased engine cooling (e.g., radiator cooling) and decreased CAC cooling depending on operating conditions.
Other attempts to address condensate formation in a CAC include controlling the lower group of grille shutters separately from the upper group of grille shutters. In this way, cooling to the CAC may be reduced while maintaining adequate engine cooling. In one example, individual control of the upper and lower groups of grille shutters may be achieved with two motors, each motor controlling one group of grille shutters. However, the inventors herein have recognized potential issues with such systems. As one example, two motors may require more complicated control routines and increased engine system components.
In one example, the seemingly paradoxical issues described above may be addressed by a method for adjusting a multi-grille shutter system with a single motor, the motor coupled only to an upper group of grille shutters. Specifically, a lower group of grille shutters may be coupled to the upper group of grille shutters through a staged linkage. The staged linkage may allow delayed opening of the lower group of grille shutters, depending on the amount of opening of the upper group of grille shutters. For example, if the upper group of grille shutters is opened less than a threshold amount, the lower group of grille shutters may remain closed. Alternatively, if the upper group of grille shutters is opened more than a threshold amount, the lower group of grille shutters opens proportionally with the upper group of grille shutters.
As one example, the multi-grille shutters system may be adjusted in response to engine operating conditions. Engine operating conditions may include engine temperature, CAC temperature, and driving conditions. In one example, only the upper group of grille shutters may be adjusted while the lower group of grille shutters remains closed in response to an engine temperature greater than a first threshold temperature when a CAC temperature is less than a threshold temperature. In another example, the upper and lower groups of grille shutters may be proportionally adjusted in response to the engine temperature greater than a first threshold temperature when the CAC temperature is greater than the threshold temperature. In this way, adequate engine cooling may be provided while reducing condensate formation and engine misfire events.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.